New soybean weed control technologies coming

Five years ago, the three hottest products in soybean weed control were glyphosate, glyphosate, and glyphosate. And if you threw in a fourth and fifth one, it would be glyphosate, too.

That's changed. The overreliance on glyphosate has spawned resistant weeds and a shift in weed species. "The Roundup Ready system has lost some of its value," says Bryan Young, Southern Illinois University weed scientist. Young spoke at media seminars at the Commodity Classic in Grapevine, Texas, in late February.

Weed resistance to herbicides isn't new. In the early 1990s, widespread use of ALS inhibitors like imazethapyr (the active ingredient in Pursuit) spawned resistant weeds later in the decade.

Reliance on mainly one herbicide has repeated itself with glyphosate. In 2006, 93% of U.S. soybean acres received an application of glyphosate. Young notes estimates posted on the International Survey of Herbicide Resistant Weeds Web site (www.weedscience.org) suggests glyphosate-resistant marestail (horseweed) currently infests 5 million acres or more U.S. crop acres.

That was reinforced by a 2008 survey of southern Illinois agricultural chemical retailers, who tagged marestail as that regionâ€™s biggest weed challenge.

"Years ago, you couldn't have found it anywherein significant densities or frequencies," says Young. "Glyphosate is a wonderful tool and we will continue to work with it, but we need new chemistry and residual herbicides."

Five years ago, the three hottest products in soybean weed control were glyphosate, glyphosate, and glyphosate. And if you threw in a fourth and fifth one, it would be glyphosate, too.

They're coming. New soybean weed control tools coming down the pike listed by Young include: